Passage behavior and survival of radio-tagged yearling chinook salmon and juvenile steelhead at Lower Monumental Dam, 2006

In 2006, NOAA Fisheries evaluated passage behavior and estimated relative survival for radio-tagged river-run hatchery yearling Chinook salmon Oncorhynchus tshawytscha and juvenile steelhead O. mykiss at Lower Monumental Dam on the Snake River. Fish were collected, PIT tagged, and surgically implanted with a radio transmitter at Lower Monumental Dam. Treatment groups were comprised of 1,398 yearling Chinook salmon and 1,171 juvenile steelhead released 7 km upstream from Lower Monumental Dam. The reference groups were comprised of 1,183 yearling Chinook salmon and 998 juvenile steelhead released into the tailrace of Lower Monumental Dam. Releases occurred during both daytime and nighttime operations for 26 d from 2 to 27 May. Project operations during the evaluation included bulk spill 24 h per day. River flow, percent spill, and tailwater elevation during releases averaged 139 kefs, 26%, and 443 ft msl, respectively. Contract no. W68SBV92844866